1. Field of the Invention
The present invention relates generally to an image forming apparatus in which a photosensitive sheet coated with light and pressure sensitive microcapsules containing photohardening materials and coloring dyes is superimposed and pressed on an image receiving sheet coated with a developer that reacts with the coloring dyes to develop colors, thereby forming an image, and more particularly to an image forming apparatus including a sheet transport device for transporting the photosensitive sheet and the image receiving sheet.
2. Description of the Prior Art
When a photosensitive sheet coated with light and pressure sensitive microcapsules containing photohardening materials and coloring dyes is exposed to light reflected from a document or any other object, the microcapsules exposed to the light harden to form a latent image. On the latent image, an image receiving sheet coated with developer that reacts with the coloring dyes contained in the microcapsules is superimposed and pressed together, thereby causing unhardened microcapsules to rupture and the coloring dyes contained therein to flow out onto the image receiving sheet, to develop the latent image. After such a pressure developing process, the two sheets are separated from each other at a separation section, and the photosensitive sheet is taken up on a takeup shaft, while the image receiving sheet is transported, for example, by means of a transport roller, to a glosser unit where it is treated with heat.
Normally, when the pressure developing process is completed, the leading edge of the image receiving sheet has reached the glosser unit, or at least as far as the transport roller. Since the leading edge of the image receiving sheet separated from the photosensitive sheet is pulled by the glosser unit or by the transport roller to further transport the image receiving sheet, transportation of the photosensitive sheet is stopped upon completion of the pressure developing process.
However, when the image receiving sheet is thus transported while transportation of the photosensitive sheet is stopped upon completion of the pressure developing process, since the portion of the image receiving sheet which is not separated from the photosensitive sheet drags along the photosensitive sheet, there is a possibility that the image formed on the image receiving sheet may be smeared. Also, since the image receiving sheet is transported dragging along the photosensitive sheet, transportation of the image receiving sheet by the transport roller, etc. may become unstable, and the image receiving sheet may not be completely separated from the photosensitive sheet. Furthermore, with the extra load applied to the image receiving sheet, transport failure may result or wrinkles may be formed in the image receiving sheet.
Accordingly, it is an objective of the present invention to provide a sheet transport control device by which the image receiving sheet can be completely separated from the photosensitive sheet, thereby preventing the smearing, transport failure, etc. of the image receiving sheet.